I've had an RCBS collect bullet puller for 40+yrs. Have 6 or 7 collets.
Great for Rifle bullets that show bearing surface above the crimp.
WILL NOT work on most Jacketed pistol bullets. Worthless on cast.
The impact hammers are great. Just like an eraser on a pencil. It's great for a few mistakes.
Try doing 150 .44Mags with one. The harder the surface you smack them on, the better they work.
The tighter the bullet pull & crimp ? The more "smacks" you'll need.